Underfeed stoker equipment



. 6, 1938. M. E. YEAGER UNDERFEED STOKER EQUIPMENT Filed June 30, 1934 7 Sheets-Sheet l lnvenTor. Milburn E.Yeu gem WW M M ATTys.

Dec. 6, 1938. M. E. YEAGER 2,139,144

UNDERFEED STOKER EQ UI PMENT Filed June 30, 1934 7 Sheets-$heet 2 lnvenTor.

MiHSurn E.Yeu e'r 03 byMMkM Dec. 6, 1938. I YEAGEfi 2,139,144

UNDERFEED STOKER EQUI PMENT Filed June 50, 1934 7 Sheets-Sheet 4 lnvenToT. Milburn E.Yeqger byimdMkM ATTys.

Dec. 6, 1938. YEAGER 2,139,144

UNDERFEED STOKER EQUI PMENT Filed June 30, 1964 7 Sheets-Sheet 5 lnvenTor.

Milburn E.Yeager WMWX M AITys.

Dec. 6, 1938. M. E, YEAGER UNDERFEED STOKER EQUIPMENT Filed June 30, 1934 7 Sheets-Sheet 6 lnvenTor. Milburn E.Yea

ger "M bym ATTys.

Patented 6, 1938 PATENT OFFICE UNDEBFEED STOKER EQUIPMENT 'Milburn Edgar Yeager,

West Somerville, Mass.,

.assignor to National Engineering & Manufactuning Company, a corporation of Rhode Island Application June 30, 1934, Serial No. 733,238

r 13 Claims.

This invention relates to improvements in stokers for furnaces and the general object thereof is to provide a stoker construction, for supplying air and for feeding fuel to a furnace, whichwill be of simplified constmction and of economical operation.

A further object of the invention is to provide a stoker construction which can be built and assembled as a unit and applied to usual furnace constructions.

More specifically one of the objects of the invention is to providea ram boxand ram with power applying means for reciprocating the ram and means intermediate 01' the power applying 1, means and ram yieldable in the feeding movement of the ram to resistance in excess of a predetermined amount by means of which the amount of fuel fed to the furnace. will be automatically and accurately controlled and which, by 1 yielding to unusual resistance, will prevent injury or breakage of the power applying or power transmitting means.

Another object of the invention is to provide a v novel wind box construction in which the vertical 7", sides of the wind box are formed of wide structural: bars, such as channel bars, preferably of structural steel, adapted to extend through the furnace and .to project beyond the front wall thereof to provide within the furnace a support 30 for the tuyeres and outside of the furnace a support for the hopper, the fan or fansfor supplying air to the burning fuel 'in the furnace and also to support the motor andthe power transmitting mechanism for actuating the ram.

Another object of the invention is to provide a pair of parallel wind boxes of the character described with a plate, preferably in the form of an inverted, channel, connecting adjacent sides of two parallel wind boxes intermediate of their width and providing outside of the furnace the base of a ram box and within the furnace the base of a retort for an under-feed furnace.

Another object of the invention is to provide an under-feed stoker construction of the character described in which the actuating mechanism for the ram may be mounted upon the channels of the wind box at a greater distance from the front of the furnace than that upon which the fan or fans are located, thereby permitting the use of a 50 long connecting rod mechanism between the ram and its actuating mechanism which will permit the application of power to the ram in approximately the horizontal plane of the ram.

A further object of the invention is to provide 5 a construction of the character specified in which a driving motor may be mounted upon the channels forming the sides of the wind box and a power transmission unit also mounted upon said channel bars in such manner as to apply power to the ram in proximity to the median horizontal plane of reciprocation of the ram.

; Another object of the invention is to provide an improved hopper and hopper throat plate construction which will enable the hopper to be placed adjacent to or more remote from the front of the furnace as conditions require.

A further feature of the invention consists in providing means for effectively sealing the possage from the hopper to the ram which will prevent fuel from entering the ram box outside of the fuel-receiving portion thereof.

Another object of the inventionis to provide an under-feed stoker mechanism having a plurality of wind boxes with a fan for supplying air to each wind box and means for independently regulating the amount of air delivered .to the respective wind boxes.

Another object of the invention is to provide a ram box having a. ram presenting flat upper surfaces forming a bottom for the hopper with a shouldered portion to engage and advance the fuel into the retort and a supplemental ram having means for advancing and for agitating the fuel in such manner as to insure uniform delivery of fuel to the fuel bed of the furnace. A

Another objectof the invention is to provide an improved form of tuyere bar construction which will effectively prevent fuel and ashes from entering the wind box and which comprises means providing a Venturi-like action to increase the force of the air supplied to the ports of the assembled tuyre bars.

. A further feature of the invention comprises a novel construction and assemblage of dump grates so associated with the tuyeres as to insure complete combustion of the fuel and convenient dumping of the ash.

Another object of the invention is to provide a construction of the character described comprising parallel wind boxes with the ram box and tuyre therebetween of the character above described in which the air may be supplied to both the wind boxes from a single fan and which comprises dead plates to receive the ashes delivered from the fire-bed from which they may be raked 50 out through the front of the furnace.

These'and other objects and features of the invention will more fully appear from the following description and the accompanying drawings and will be particularly pointed out in the claims. r,

Preferred embodiments of the invention and details of construction are illustrated in the accompanying drawings, in which,

Fig. 1 is mainly a vertical longitudinal central sectional view through the ram box, the hopper for supplying fuel thereto, and the retort, illustrating certain portions of the driving mechanism and the tuyeres in elevation;

Fig. 2 is a plan view of the construction shown in Fig. 1 as assembled in a furnace, the hopper not being shown;

Fig. 3 is a vertical transverse sectional view on line 3-3 Fig. 2, through ,the wind box, the retort therebetween and the shafts for the dump grates, the latter being shown in elevation;

Fig. 4 is a detail view showing the latch mechanism for locking the dump grates in horizontal position;

Fig. 5 is a detail end view of the portion of the assembled tuyeres;

Fig. 6 is a transverse sectional view on line 68 Fig. 2 through the wind box, the ram box and ram therebetween and the hopper plates;

Fig. 7 is a side elevation of one of the wind boxw, the hopper plates, and a portion of the hopper mounted thereupon;

Fig. 8 is a vertical sectional view on line 88 Fig. 2 of the power transmitting mechanism mounted upon .the channel bars forming the sides of the wind box;

Fig. 9 is a vertical sectional view of the power transmitting mechanism on line 8-9 Fig. 8;

Fig. 10 is a plan view similar to Fig. 2, illustrat- -ing a modified under-feed stoker construction embodying the invention; and,

Fig. 11 is an enlarged detail sectional view on line II-II Fig. 10.

The invention is illustrated in the accompanying drawings as embodied in an under-feed stocker, although certain features of the invention, particularly the mechanism for feeding fuel to the furnace, the tuyeres, etc., may be embodied in other types of furnaces.

One of the objects of the invention as above pointed out is to provide an under-feed stoker construction which when assembled is of a uni- 'tary character adapted to be embodied in a. usual type of furnace, such as a water tube or fire tube furnace, or other heating apparatus, and comprises a base frame of rigid construction in which the side walls of the wind boxes are formed of wide structural bars, preferably structural steel channel bars, which serve to support the ram box, a ram and its actuating mechanism, the hopper for feeding fuel to the ram box, the retort, tuyeres, and dump grates, and which also supports the fan or fans for supplying air to the wind boxes, as will more fully appear.

As illustrated in the drawings two parallel wind boxes are provided which extend from outside of the furnace through the front wall of the furnace and preferably to the rear wall thereof. One of the wind boxes has side walls I and 2 formed of wide channels, preferably of structural steel, with the lower flanges thereof facing each other and resting upon a suitable rigid bed 3, such as concrete, with the upper flanges 4 and 5, which face each other, supporting certain mechanisms here inafter described. The other wind box is formed ing upon the bed 3 with upper flanges 8 and 9 similarly supporting other mechanisms.

76 The adjacent channels! and 6 of the parallel wind boxes are spaced apart and a plate III, preferably in the form of a structural steel channel having downwardly extending flanges, is bolted or otherwise secured to the webs of the channels 2 and 6 intermediate of the width thereof to provide outside of the furnace the bottom of a ram box, and within the furnace the bottom of a retort into which the fuel is fed by the ram and from which it is forced into the burning bed of fuel and over the tuyeres and the unconsumed material finally delivered to dump grates or to a bed plate, as will hereinafter more fully appear.

The sides of the ram box desirably are provided with steel lining plates I I, which are spaced apart at their ends by blocks I2, which desirably are welded to the plates I I and welded or other-' wise secured to the webs 2 and 6 of the wind box.

The rear ends of the plates I I are provided with recesses I3 (see Fig. 2) which are engaged by complementary projections upon cast iron liners I4 for the sides of the retort. The opposite ends of the liners I 4 are provided with projections to engage complementary recessed portions in the sides I5 of a tuyere box end which is located at the rear end of theretort as shown in Figs. 1 and 2, and has an inclined web I6 connecting the sides I5 and provided at its upper edge with a rearwardly extending flange'which is engaged by a complementary transverse recess in an apertured extension plate H which extends outwardly over and is supported upon the upper flanges 5 and 8 of the channels forming the side walls of the wind boxes.

By reason of this construction the tuyre box end may be removed and the liners l4 drawn rearwardly a short distance to disengage the joint formed by the projection and recesses I3 so that the liners for the retort may be conveniently removed and replaced.

The side walls of the channel bars may be cut away beneath the tuyere box end to provide apertures I8 through which air under pressure may be forced through the tuyere box end when both bars are apertured and serve to provide communication between the wind boxes at the rear end of the furnace. The rear ends of the wind boxes are closed with suitable plates and the front end of the wind boxes provided with suitable detachable doors I9.

Suitable tuyeres, formed of juxtaposed tuyere bars 20, preferably of a character hereinafter to be more fully described, are slidably and detachably mounted upon the upper flanges 4, 5, and 8, 9, of the respective wi'nd boxes within the furnace, and form the tops of the wind boxes. The inner end portions 2| of the tuyere bars preferably are in alinement with the upper edges of the liners ll of the retort and form extensions thereof as shown particularly in Fig. 3.

One of the principal features of the invention comprises novel mechanism for feeding fuel to the retort and while the feeding mechanism forming an essential feature of the present invention is shown herein as applied to an under-feed stoker, it is adapted to be embodied in other types of furnaces as will be readily understood by those skilled in the art.

The principal object of the feeding mechanism of this invention is to provide means, such as a ram for forcing the fuel into the retort or into the furnace, with yieldable means interposed between the ram and the actuating mechanism therefor of such character-that it will serve to maintain an even fuel bed and will yield to unusual resistance of the fuel bed or to an obstruction without danger of breaking the ram, the

actuating mechanism or the means for transmitting power therefrom to the ram.

The feedingmechanism illustrated herein comprises a ram having vertical sides 22 (see Figs. 1

and 6) connected by'an integral top plate 23,

adapted to form the bottom of the hopper throat, and a vertical fuel engaging and feeding face 24. A shaft 25, which extends through the sides 22, forms the pivot for the head-26 of a connecting rod 2!v which'is slidably mounted in a sleeve 28 which has a web 29 provided with a journaled bearing 30 for a crank SI of power transmitting mechanism for reciprocating said sleeve and said connecting rod. A spiral spring 32, which is coiled about theconnecting rod 21, is interposed between the head 26 of the connecting rod and a flange or "collar on the adjacent end of the sleeve 28. v I

By reason of this construction the ram is forced forward by pressure of the sleeve against the spring which transmits said pressure to the ram. The ram therefore is enabled to yield to resistance in excess of a predetermined amount; whether such resistance is by reason of accumulation of material in the retort or caused by an obstruction in the retort throat or otherwise. The danger of breakage of parts which has been a serious defect in stokers heretofore constructed is thereby eliminated.

. In order to control the rate of feedof fuel to the retort or furnace means are provided for controlling the effective length of reciprocation of the ram by the power applying mechanism. This is accomplished, by providing an adjustable abutment adapted to be engaged by the other end of the sleeve during the portion of the rotation of the crank 3| which withdraws the ram after its feeding movement. Any suitable adjustable abutment may be provided, In the preferred construction illustrated the end portion 33 of the connecting rod 21, which projects beyond the sleeve, is screw threaded and provided with a nut 34 which may be positioned to give any desired amount of lost motion between the nut 34 and the adjacent end of the sleeve. It will,- therefore, be obvious that by adjusting the amount of lost motion the distance which the ram will be withdrawn from its maximum feeding position may be accurately determined. 1

In the construction illustrated the ram is forced during its normal feeding movement to a position in which the vertical face 24 of the ram reaches or enters slightly into the throat of the retort. The retort is provided with a throat plate the face of the front wall 38 of the furnace and has anupwardly and rearwardly inclined integral whi ch receives the upturned end 4| of a suppleretort and isluided' in arecess 43 mentairam 42; preferably in the form of a redtangular bar, which lies upon the base ill of the inclined plate; I 8 of tuyre end. i

vertical flange 31 of the hopper throat.

in-theflowei' The supplemental ram bar has secured to it and at intervals wedges 44. the rear faces of which are considerably more abrupt than the front face. These wedges act during the reciprocation of the ram to agitate the material and by reason of the more abrupt inclination of the front edges thereof to force the fuel upwardly and rearwardly inthe retort and over the tuyre bars which extend laterally from the edges of the retort, as illustrated in Figs. 2 and 3.

Any suitable means may be provided for supplying fuel to the ram box. In the present invention fuel is supplied by a hopper to a chamber formed by hopper plates located below the hopper and so constructed that a short or a long hopper throat may be employed in accordance with the requirements of the installation. As illustrated in Figs. 1 and 2 a long hopper throat is provided. The hopper throat in this construction comprises two pairs of alined hopper plates, one plate of eachpair abutting end to end with a transverse plate closing the forward end of the hopper throat. Each of these hopper plates, as illustrated'more particularly in, Fig. 6, comprises a casting having a downwardly inclined side wall 45 which extends to or slightly beyond the vertical plane of the ram box lining l I. The hopper plates are provided at their lower sides with laterally extending flanges 48 which extend over and are supported by the flanges 5 and 8 of the inner vertical channel bars 2 and 6 of the wind boxes. Each of these hopper plates is provided at its ends with vertical flanges 41 adapting the same to be secured to each other and to the The outer end of the hopper throat is provided with an end throat plate having an inclined wall 48, a bottom flange 19 and vertical side flanges ill which lie between and are secured by bolts II to the outer hopper side plates 45.

In the cpnstruction shown the hopper comprises a downwardly tapering body portion 52 and a more abruptly downwardly tapering lower portion 53 which is supported within a cover plate 54 plate 54 placed over the hopper plates adjacent the end and the hopper throat plate 48 moved up to close the end of the hopper throat chamber as will be readily understood. This adiustability to provide either a long 'or short hopper throat is advantageous in installations where there is not suflicient room for the long hopper throat on the one hand, and upon the other where it is desired that a long hopper throat shall be used in order that the atendant may observe the flow of fuel from the hopper into the retort. I

In order to prevent any of the fuel from sifting f into the hopper box down the sides or over the wind boxes.

end, are preferably bent downwardly and upon assembly forced into frictional engagement with the flat plate 23 which forms the top of the ram and provides an efiective seal for preventing fuel from sifting into the ram box as the ram is reciprocated.

In the present construction fans for supplying air to the wind boxes are located in front of and in proximity to the hopper while the power applying mechanism for actuating the-ram is located in front of the fans. This is permitted by the provision of a long connecting rod for transmitting the power from the power applying means to the ram and is of great advantage over prior constructions in which the means for actuating the ram have been located between the fans for supplying air to the wind boxes and the furnace. One of the advantages obtained is in the employment of a long connecting rod which is in substantially the median horizontal plane of the min during the feeding movement so that a substantially direct thrust is imparted from the crank of the power applying means to the ram, thereby lessening friction between the ram and the base of the ram box and enabling a maximum amount of power to be transmitted from the actuati mechanism to the ram.

The channel bar construction of the sides of the wind boxes enables a fan unit or units to be mounted directly upon the channel bars and also permits the mounting of a power transmitting unit directly upon the wind box channel bars. In the construction illustrated in Figs. land 2, the cover plates 66 extend from the front wall of the furnace over each of the wind boxes to the end thereof and form closures for the wind boxes. Fan housings 51 having suitable base flanges are supported by and secured to the upper flanges 4, 6, and 8, 9, on the side channel bars of the A motor 58, which may be an electric motor, turbine, or other power producing unit, is located between the fan housings and supported by a suitable frame which rests upon and is bolted to the flanges 5 and 8 of the inner channel bars of the wind boxes. Suitable fans (not shown) are mounted upon the ends of the motor shaft 59 and recesses are cut in the cover plates 56 to coincide with the outlets of the fan houslugs and thereby permit the air from the fan to be forced into the respective wind boxes.

One of the features of the invention comprises means for controlling the amount of air delivered to the respective wind boxes. In the construction disclosed the outer walls of the fan boxes are recessed to provide an inlet for the fans which desirably are of the squirrel cage type and suitable adjustable dampers 60 placed in the inlets enable the amount of air drawn into the fan, and consequently delivered to the wind boxes, to be accurately controlled.

As illustrated herein the motor shaft 59 is provided with a sprocket gear 6| from which a sprocket chain 62 drives the sprocket pinion 63 upon apower transmitting mechanism for actuating the crank which reciprocates the ram. This power transmitting mechanism is of the speed reducing type and preferably is in the form of a unit having a suitable casing 64 which is supported upon and bolted to the upper flanges 8 and 9 of the channels 6 and I forming the sides of one of the wind boxes. The sprocket pinion 63 drives a shaft 65 'mounted in bearings in the casing having a worm 66 which engages the worm wheel 61 upon a shaft 68 which is mounted in bearings in a portion of the housing depending into the wind box. The shaft 68 has upon it a worm 69 which drives a worm gear I0 upon a shaft 'll which is located above the wind box and is provided at its end with a crank arm 12 having at its end a crank 3| which engages the bearing 30 in the web 29 of the sleeve 28 through which power is transmitted to the ram. By reason of this construction therefore a standard motor for operating fans of a standard type can be readily utilized and power transmitting 'units of a suitable design may be employed, thereby enabling a great economy in expense over usual types of mechanisms requiring specialized construction as has hitherto been necessary.

It has heretofore been stated that the tuyeres form the covering for the wind boxes within the furnace. In the present construction the tuyeres are of a novel and improved construction and comprise a series of similar or reversely arranged tuyere bars 20 for the tops of the respective wind boxes. Each of these tuyere bars is of skeletonized construction having an inner base 13 which rests upon the flange'i or 8 and has a downwardly extending under-cut portion 14 which is slidably mounted upon the upper flange 5 or I of the channel bar side 2 or 6 of the respective wind box. The body of the tuyere bar extends upwardly from the base presenting a' substantially vertical face 2| as before described and therefrom an outwardly inclined curved flat surface I5 having a crown I6 from which it extends less abruptly downwardly to present a substantially flat face H which merges into a horizontal foot portion I8 which projects over the outside flange 4 or 9 of the channel bar I or I and is provided Each of the tuyere bars preferably is provided with recesses extending inwardly from the edges thereof providing a series of ports 8| and 82 and at the crown smaller ports 83. .A web 84 extends from the central web beneath the ports II and along the lower edge of the tuyere bar and has upwardly extending flanges 85, while other flanges 86 extend from the web 60 throughout the width of the plate substantially horizontally beneath the ports 8| in the straight flat face l'I of the tuyre bar. Similar flanges 81 having upwardly turned end portions similarly extend from the web 66 to the edges-of the plates beneath the ports 82 along the inner curved wall 16 of the tuyere bars.

By reason of this construction apertures of a restricted area are provided between the end flanges 65 and adjacent flanges 86 leading to the ports 8| in the inclined flat surface 11 which produce a Venturi-like action upon the air which is forced from the tuyere box to the passages leading to the ports 8|, thereby increasing the velocity of the air as it is forced into the flre-bed. The flanges 81 likewise provide restricted passages which produce a Venturi-like action upon the air which is forced throughthe ports 82.

It has heretofore been mentioned that the invention also comprises dump grates which are supported upon the outer walls I and I of the channel bars which form the sides of the wind boxes. In the particular construction illustrated a series of brackets 88 are welded, or otherwise secured, to the upper portions of the vertical webs I and I forming the outsides of the respective wind boxes. A dump shaft 99 of rectangular construction is provided with cylindrical portions 99 which are rotatably mounted in the brackets 98. The dump grate bars are of novel construction each comprising a flat plate 9I having a central reenforclng web 92 merging into an enlarged inner end portion 93 which is provided with a rectangular recess to flt upon the squared portion of the dump grate shaft. The dump grate bars are secured to the dump grate shaft by bolts 94 which extend downwardly through the enlarged portions 99 of the dump grates and are provided with a collar or washer 95 which underlies the portion of the lower face ofthe dump grate shaft and is clamped'thereupon by a nut 96.

The end' of the dump grate shaft 99 extends beyond the front wall of the furnace and has secured toit a collar 91 (see Fig. 4) having a notch 99 which is engaged by the hook end 99 of a latch I99 which serve to secure the grate bars in horizontal position, as illustrated in Fig. 3. A suitable crank may be applied to the end of the dump grate shaft and upon release of the locking hook I99 from the collar 91 the crank may be operated to swing the top grate bars into .vertical position,- as illustrated in Fig. 3, to dump the ashes into the ash pit. c 1

Desirably means are provided for admitting air beneath the dump grates if the ash supported thereby contains unburned fuel and in the present invention apertureajwhich are cut through the webs of the channel bars I and I, are provided with sliding dampers I9I connected to rods I92 which may be adjusted by means of handles I93 located beyond the front wall of the furnace. The front wall of the furnace is provided with suitable hinged doors I94 which maybe opened to permit the ashes inthe ash pit to be raked out.

It will be observed that the under feed stoker mechanism comprising the presentinvention is of simple and rigid construction adapted to be assembled as a unit with all parts thereof, including the fans and their driving mechanisms,

, and the power applying and transmitting mechasides of the wind boxes.

nism mounted upon the channel bars forming the the furnace are easily accessible andwithinthe "furnace the linings for the retort and tuyere bars and the dump grates are readily removable and replaceable.

The fuel feeding mechanism is of a particularly novel character in that the ram is yieldable to resistance in excess of a predetermined amount In the operation of the device the fuel in the hopper 52 descends by gravity upon the top surface 23 of the ram which forms the bottom of the hopper throat. Upon the reciprocating movement of the ram the fuel drops in front of the vertical end 24 of the ram and during the forward movement of the ram is forced through the ram box into the retort. At the same time, during the forward movement of the ram, the fuel The parts outside of I resting upon the upper flat surface 23 is advanced into contact with the front wall 91 of the hopper throat plate. The advancing movement of the ram also causes the wedges 48 of the supplemen- I tal ram to forward the fuel in the retort and at the same time to agitate and raise it. When the retort has been fllled with fuel continued operation of the ram causes the fuel to be carried upwardly over, the crown of the tuyere bars and over the downwardly inclined flat surface thereof. Such portion of the fuel as is thus supported by the tuyeres is subjected to blasts of air issuing from ports in the tuyeres and proper combustion insured. The ashes from the burned fuel pass from the ends of the tuyere bars on to the dump grates where-it accumulates until the dump grates are dumped. Any fuel which remains in the ash after it is deposited upon the dump grates may be burned by admission of air beneath the dump grates and its passage through the narrow spaces between adjacent dump grates.

Figs. and 11 illustrate the invention as applied to a modified form of under-feed stoker construction in which dead plates are provided at the outer ends of the tuyeres to receive the ashes and other unconsimied material delivered from the fire-bed. In the construction illustrated in Figs. 10 and 11 a single fan is employed which supplies air under pressure to a singlewind box which extends through the front wall of the furside of'the retort the top of which is likewise formed by the tuyeres and a dead plate.

The mechanism for supplying air to the wind box may be and desirably is the same or similar to that heretofore described. The construction of the ram box, ram, and the mechanism for actuating the ram also may be and desirably is the same or similar to that heretofore described. In the construction illustrated in Figs. 10 and 11 the wind box comprises side walls I95 and I99 formed of wide channels, preferably of structural steel, with the lower flanges facing each other and resting upon a suitable rigid bed, such as concrete, and with the upper flanges I91 and I99 which also. face each other, serving to support the fan housing and fan and also serving as one of the supports for the motor. I I

The channel bar I99 desirably extends through the furnace to the rear end thereof, while the channel bar I95 terminates preferably at the inner face of the front wall I99. An angle bar III] having an upper flange I II of the same width as the flange I91 abuts against the end of the channel I95 and extends through the furnace in parallelism with the channel I95 and is supported upon suitable brackets I I2 welded or otherwise secured to the channel bar I96. Tuyere bars II3, which may be and desirably are the same or similar to the tuyere bars 29 heretofore described, are slidably mounted upon. the flange I98 of the channel bar I96 and the flange III of the angle bar H9. The lower ends II4 of the tuyere bars extend horizontally across and preferably beyond the angle bar ii I. An angle bar II5relatively lighter than the angle bar II9 extends longitudinally thereof and is welded 15 thereto with its horizontal flange IIO sumciently lower than the plane of the upper surface of the flange III to receive the offset edge ill of a flat dead plate IIO, the upper surface of which desirably is flush with the upper surface'of the tuyere bar ends H4. The outer edge of the dead plate IIO may be supported in any suitable manner as by brick-work II 9 built against the side wall of the furnace.

The rambox and ram and the retort are of the same construction as that heretofore described differing only in that a single channel bar I20 of' the same width and equal in length to the channel bar I00 extends in parallelism with the channel bar I00 throughout its length and is spaced apart therefrom by a horizontal plate I2I preferably in the form of a channel bar having down wardly extending flanges secured to the webs of the channel bars I00 and I20.

The channel bar -I2I forms the base of the ram box and also forms the base of the retort as heretofore described. The rain box may be and desirably is provided with steel lining plates (not shown) and the retort with cast iron liners 35 I22 which may be constructed and secured in place in the manner heretofore described. The tuyeres H3 at the opposite side of the retort than those heretofore described are slidably mounted at their inner ends upon the upper flange I23 of vt0 the channel bar- I20 and at their outer ends are slidably mounted upon the horizontal flange I24 of an angle bar I20 which is supported upon suitable brackets I20, similar to the brackets II2, welded or otherwise secured to the channel bar as I20. A smaller angle bar I2'l extends longitudinally of'and is secured to the angle bar I25 and serves to support the offset edge of a dead plate. I20, the outer edge of which rests upon a suitable support I20, such as brick-work extending 40 along the wall of the furnace.

The webs of the channels I00 and I20 are provided near the rear of the furnace with apertures I00 and IOI beneath a tuyere box end I02 which desirably is the same or similar-to that previously 5 described. Air under pressure supplied from the wind box to the chamber I will, therefore, be

forced through the apertures I20 and Ill beneath the tuyere box end I32 into the chamber I24. The chamber I04 has a dead front end and 50 the air under pressure accumulating in the chamber I04 will therefore be forced through the ports of the tuyeres III forming a portion of the top of said chamber into the portion of the fuel bed resting thereupon.

As heretofore stated the fan mechanism for supplying air to the wind box. the driving motor and the power transmission mechanism actuated thereby to reciprocate the ram, may be in all respects the same as that heretofore described. As illustrated in new a fan housing In is mounted upon the webs I01 and I00 of the channels I00 and I00. A fan, preferably of the squirrel cage type, is mounted in the housing and is supplied with air through an air inlet at the eye of the fan.

Suitable means for regulating the effective area of the air inlet are provided. As illustrated in Fig. 10 two dampers I 20 of the butterfly type are 70 mounted upon vertical pivots in the fan housing and provided with arms I" which are connected to a link I00 by means of which they may besimultaneously adjusted to vary the effective area 7 of the fan inlet. A motor I" is mounted upon 75 the flanges Ifland I20 of the channel bars I00- I and I20 and the motor thereof desirably is directly connected to the fan.

Suitable power transmitting mechanism I40,

such as that above described, is mounted upon a base plate I which is supported by suitable brackets (not shown) from the channel bar I20. The motor I39 is provided with a suitable sprocket gear I42 for transmitting power through a sprocket chain I to the power transmitting mechanism which reciprocates a sleeve I44 which is slidably mounted upon a connecting rod I40, the opposite end of which is connected-to the ram, and the power applied thereto through a spring interposed between the sleeve and the head of the connecting rod, as heretofore described, in respect to the construction illustrated in Fig. 1.

The construction of the hopper and the hopper throat providing for either a long or a short throat, and other elements of the feeding mechanism, may be and desirably are the same as those heretofore described.

It will be understood that various modifications in form, construction and arrangement of parts may be made and that many features of the invention may be employed in stokers for other forms of furnace than those herein specifically described, and therefore that the particular embodiments of the invention are of an illustrative character and not restrictive of the meaning and scope of the following claims.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

1. An underfeed stoker assembly, a furnace having a flat floor and a front wall, comprising two spaced parallel wind boxes within said furnace, the adjacent sides of said wind boxes extending through and well beyond the front wall of the furnace, a horizontal plate extending longitudinally of the said adjacent sides and secured thereto and forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace.

2. An underfeed stoker assembly, a furnace having a flat floor and a front wall, comprising two spaced parallel wind boxes within said furnace, the adjacent sides of said wind boxes extending through and well beyond the front wall of the furnace, a horizontal plate extending longitudinally of the said adjacent sides and secured thereto and forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace, a tuyere box at the end of said retort communicating with said wind boxes and having a surface inclined upwardly to permit fuel from said retort to flow over the sides of said retort.

3. An underfeed stoker assembly. a furnace having a flat floor and 'a front wall, comprising two spaced parallel wind boxes within said furnace, the adjacent sides of said wind boxes extending through and well beyond the front wall of the furnace, a horizontal plate extending longitudinally of the said adjacent sides and secured thereto and forming with the sides of said wind boxes 9. retort within the said furnace and aram box outside said furnace. a tuyere box at the end of said retort communicating with said wind boxes and having a surface inclinedupwardly to permit fuel from said retort to flow over the'sides of said retort, lining plates secured to and spaced apart from the sides of the ram box, and liners for said retort.

4. Anunderfeed stoker assembly, a furnace having a flat floor and a front wall, comprising two spaced parallel wind boxes within said furnace, the adjacent sides of said wind boxes extending through and well beyond the front wall of the furnace, a horizontal plate extending longitudinally of the said adjacent sides and secured thereto and forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace, an end hopper 1o throat plate anda plurality of pairs of hopper throat plates mounted. upon the said adjacent wind box sides in front of said furnace;-. and a hopper mounted upon said hopper throatplates remote from the front wall of the furnace leaving a space between the hopper and the front wall of the furnace for observation of and access to the fuel being fed to the furnace, said hopper communicating with said ram box.

5. An underfeed stoker assembly, a furnace having a flat floor and a front wall, comprising two spaced parallel wind boxes within said furnace, one of said wind boxes and the adjacent side of the other wind box extending through and well beyond the front wall of the furnace, a

horizontal plate extending longitudinally of said adjacent sides and secured thereto and forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace, a hopper mounted on the adjacent wind box sides in front of the front wall of said furnace and communicating with said ram box, a motor mounted on the adjacent wind box sides in front of said hopper, a fan driven by said motor mounted in a casing communicating with the wind box whichextends through the front wall of said furnace, a ram -reciprocably mounted in said ram box, and power transmitting means driven by said motor for actuating said fan mounted in front of said motor, thereby permitting the use of a long pitman rod for reciprocating said ram and consequent application of power to the ram substantially in the direction of the axis of its reciprocation.

6. An underfeed stoker assembly, a furnace having a flat floor and a front wall,- comprising two spaced parallel wind boxes within said furnace, and extending through and well beyond the front wall of the furnace, a horizontal plate extending longitudinally of said adjacent wind box to sides and secured thereto and forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace, a hopper mounted in front of said front furnace wall, said hopper communicating with said ram 55 box, a motor mounted in front of said hopper,

fans mounted upon the shaft of said motor, housings enclosing said fans communicating with the respective wind boxes, and means for adjusting the areas of the inlets'to said housing whereby the pressure of the'air in the respective wind boxes may be regulated.

7. ,An underfeed stoker assembly, a furnace having a flat floor and a front wall, comprising 65 two spaced parallel wind boxes, the adjacent sides of said wind boxes extending through and well beyond the front wall of the furnace, a horizontal plate extending longitudinally of said adjacent wind box sides and secured thereto and 70 forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace, a series of contiguous tuyere bars forming the tops of said wind boxes within the furnacehaving end portionsslidably and detachably mounted upon the adjacent windbox forming with the sides of said wind boxes a retort within the said furnace and a ram box outside said furnace, a series of contiguous tuyre bars forming the .tops of said wind boxes within the furnace having end portions slidably and detachably mounted upon the adjacent wind box 1 sides, and at their inner endsextending upwardly and curving outwardly forming extensions of the walls of said retort and thence extending more gradually downwardly and outwardly to provide supporting surfaces for the burning fuel 20 and having means to prevent admission of fuel or ash to the wind boxes.

= 9. In an underfeed stoker assembly for furnaces, a wind box, tuyres positioned on said wind box, a retort associated with said'wind box, 25

a ram box in alignment with and communicating with said retort, a ram movable in said ram box, power means for reciprocating said ram, a coal hopper, and a conveyor device operated by said ram for receiving coal from'said hopper, 30

said conveyor device comprising means whereby movement of said ram towards the furnace carries one charge of coal forwardly towards the retort and also forces another charge of coal from the ram box into the retort, and movement 35 of the ram in the opposite direction permits passage of the conveyor charge into the rambox.

10. In an underfeed stoker assembly for furnaces, a wind box, tuyeres positioned on said wind box, a retort associated with said wind box, 40

a ram box inalignmentwith and communicating with said retort, a ram movable in said ram .box, power means for reciprocating said ram, a coal hopper, and a conveyor device secured to said ram and forming the upper portion thereof 45 for receiving coal from said hopper,- whereby movement of said=ram towards the furnace carries one charge of coal in said conveyor device forwardly towards the furnace and also faces another charge of coal from the ram box into the retort, and movement of the ram in the opposite direction permits passage of the conveyor charge from the conveyor device into the ram box.

' 11. In an underfeed stoker assembly for furnaces, a wind box, tuyres positioned on said wind box, a retort associated with said wind box, a ram box in-alignment with and communicating with 7 said retort, a ram movable in said ram box, power means for reciprocating said ramincluding and pressure member contractible upon excessive ram resistance, a coal hopper, and a conveyor device secured to said ram for receiving coal from said hopper and including means whereby movement of said ram towards the furnace carries one charge of coal forwardly-towards the furnace and forces another charge 'of coal'from the ram box into the retort, and movement of the ram in the opposite direction permits passage of the conveyor charge into the ram box.

12. In-an underfeed stoker assembly for furnaces, a wind box, tuyres positioned on said wind box, a retort associated with said wind box, a ram box in alignment with and communicating with said retort, a ram movable in said ram '5 box, power means for reciprocating said ram, including a pressure member yieldable upon excessive ram resistance, a coal hopper, and a conveyor device secured to said ram and forming the upper portion thereof, for receiving coal from said hopper and having means whereby movement of said ram towards the turnace carries one charge oi! coal forwardly towards the furnace and also forces another charge of coal from the ram box into the retort, and movement of the ram in the opposite direction permits'passage of the conveyor charge into the ram box.

13. In an underieed stoker assembly for furnaces, a retort, a ram box communicating therewith, a ram in said ram box, and reciprocating means for said ram comprising a sleeve, 9. .rod slidable therein and having one end secured to the ram, and a cylindrical coil spring mounted on said rod and having an internal diameter slightly in excess of the rod diameter, said coil spring ends engaging the contiguous sleeve end and rod end, the end of said rod having a lock member adjustably mounted therein and en- 10 gaging the other end of the sleeve.

MILBURN EDGAR YEAGER. 

